Furnace construction



Jan. 11 1927.:

F'URNACE` coNsTRUcToN Filed April 9 1925 f A. y 1,614,231 'A. E. GRUNERT ET AL Patented Jan. ll, 1927./-

.enanos n.' entrainer,

and claimed Serial No. 6

for furnace ln that appli novel metlio combustion ii'iuD't S 01E' CHICAGO,

Application led April 9,

'rares PATENT orifice.

AND .ALEX 1D. BAILEY,

or LA cannon, rumors.

FURNACE CONSTRUCTION.

n relates to furnace ,con-

rticularly provides an in our co-pending application,

7 6,7 44, lil construction.

dof an cation we have d means for improving ed November 24, 1923 disclosed a of fuel, particularly in connection with stolzer fired .furnaces employing fuel having the use of a fiets of air at inwardlyan nace for the proper amou of combustible gases ris bed due to coking o We found in connec considerable series of nozzles volatile matter by for deliveringr relatively hi gli velocity directed fth with the 'device therein proportions 'the fuel bed the velocity maintained. delivery downwardly purpose of of over fire ing e fuel.

tion with our work within the fur- .delivering the air into the ban from the fuel disclosed that in order to secure proper results, the relative of over tire air to air through should be closely regulated and .of the over We found through sections should be regulated in a from whatwould air were not employed.

- been customary to upon the' excess of latter sections lire air properly also that the air of the fuel bed diii'erent manner be necessary if over fire Heretofore it has depend to a large extent air delivered through the the fuel bed where the` fuel is reduced substantially to ash and refuse.

But the air so with nor,

to the combustible gases of the fuel, and ti may be carried in passed a relatively great delivered does not in fact, come close from the coking ne particles of fuel which the draft. until they have distance from the fuel hed. n some cases into the boiler tubes.

Since, accor closed in thev'a deliver the prope ding to our invention as disforesaid application, we can r amount of air by our jet system and thoroughly mix it with the combustible gases an gases coming..

d. in from fact, the fire at or adjacent the mix all of `the region in. which they are released, the proper proportioning of ous parts of the the through vbecomes a ma According to closed, we p delivery rateto accor fire air and royide a for delivering d with the rate of fuel delivery,

the air as among the varifuel bed and as between the over lire air,

tter of prime importance.

the invention herein dise# common. source of air air lat the proper k be regulated the art with the manner voperating a device embo i925. sensi No', 21,779.

d vice and the under fire air delivery device to this common source. The proper proportioning of over fire airand through tire air may be determined upon for a given 'grade or quality .of fuel and a .given character of fuel bed. Change in the rate of fuel being burned may require merely an increase in rate of air delivered from the common source.

For a different grade of fuelJ or thickness or character of fuel bed they relative pressures of air supplied to the over re an under fire air delivery devices .may have to y to secure the proper proportioning of air over orthrough the fire.

We provide a series of separate air boxes under the refed .from the common blower through control valves so that the relative proportioning of air as between the sections of the fire may be regulated and also by a common adjustment of these valves the rela tive delivery as between the over lire and through lire air may be controlled.

In addition, we provide as an optional feature a booster blower between the vcome mon source of air supply and the over fire nozzles, so that thereby the .relativepressure may be varied and the velocity of the air delivered at, thevjets may always be maintained. We are aware that it is broadly old to admit air over the tire and through the fire from a common source, as shown for example, in the patentvto Lishman, No. 477,- 37 6, June 21, 1892, but in all prior devices so far as we know where such common source. of air supply was provided, no trav cling bed of fuel has been maintained with the necessity for proportioning the air delivery in the respective sections of the fuel bed, and the necessity for maintaining ahigh velocity of the over tire air delivery means. The distribution means for distrib uting the air through the sections of the fuel bed affects at'the same timethe relative proportions of over fireV and through fire air from the common source.

Now, in order to acquaint those skilled in of constructing and dying our invention. wev shall describe in connection with the ac- 'rrcompanying' drawing a specific embodiment@ lof the same.

Figure' 1' is v'a longitudinal vertical secdos y tion throughthe lower part of a furnace and stoker construction showing 1n somewhat d1- Vagrammatic form the air connections; and

. The furnace with which I have elected to The furnace may be divided per v(not shown),

' 4chain grate 28, 29, 30 and illustrate my invention is of substantially the same type .as shown in my prior application above referred to, to which reference is here made for a more detailed description. The

furnace includes a back Wall 10 which has a forwardly projecting `portion or arch overhanging the discharge end of the grate and a frontwall 14 below which there is formed a forwardly extending flat arch 16 joining the vertical wall 14 by a rounded knee 15, between which knee and the forward projection 60 on the rear wall there `is formed a throat or narrow portion of a fire-box 11 which extends above the throat.

tions each having a stoker therein as by means of the low wall 12. In this manner two vs toker sections may be located under the same boiler, which is not shown.`

The arch 16 is suspended from suitable supporting frame work-and forms a suitable ignition arch above the forward part of the stoker 21, which stoker comprises a traveling chain grate 22. The front part of the arch 16 terminates in a front wall 17, which is formed of firebrick and which overlies the forward part of the fuel gate 61 by which the depth of fuel bed upon the chain grate 22 is determined. The entire interior of the furnace walls is lined with a suitable refractory, preferably firebrick, as is wellunderstood by those skilled in the art.

Fuel is fed onto the grate 22 from a suitable hopper 23 which is supplied with fuel bya spout extending from an overhead hopas is well known to those skilled in the art.-

Air is supplied to the fuel bed 24 on the 22 through a series of ducts 27, 31, each of which ducts has a suitable control valve 82 therein. These ducts extend from a wind box 25, into which air is delivered at a suitable pressure from a blower 26. IThe ducts 27 to 31, inclusive.

, deliver into chambers, 62, 63, 64, and 66.A

respectively, these chambers being formed under the grate 22, so that different pressures may be carried fuel bed, and so at different portions of the that the delivery ofair to the respective sections of the fuel bed may suitably be controlled.

The fuel' with which we hac employed the construction her-cin shown comprises Illinois and Kentucky soft coal of screening size. This coal contains 'a relatively high percentage of volatile mattei', analyses showing of the order of 39% volatile matauxiliary wind-box 50 from which a series' of nozzles project through the forward wall 17 immediately under the arch 16, these nozzles being directed inwardly and diagonally downwardly into the general zone of formation'of a bank of combustible gases. The plenum box is connected by a conduit 51 with the main wind box 25 so that the fan or blower 26l supplying air fire.` l/Ve also provide a er 52 in the conduit 51-so that the air in the plenum box-50 may be maintained at a suitable pressure to secure the desired velocity effect from 4the nozzles 53.

through the fire and above the forms the common means for u supplementary blow# rsis The nozzles 53 may be spaced at intervals across the width of the wall 17 so `asto secure'the desired effect of air delivery and the desired mixing, effect within the furnace, as

will be referred to later.

In operation, the coal entering under the gate 61 from the hopper 23 is ignited from the heat reflected from the arch 16 and the wall 17, and only a relatively small amount of air is delivered into the entering fuel from the chamber62. As soon as the fue l is ignited it begins occurs, this coking effect being most proto give ofi combustiblegasses because of the coking effect v vhichmoA nounced over the chamber 63, as indicated by reference numeral 36, andtc part over the chamber 64,as1- reference numeral 37; The.'r coking is accomplished bythe tlm t fuel burns asa fixed of chamber 64. chamber 66. duced to ashes 39, and it is discharged at the rear'end of the traveling grate 22 into pit (not shown).

over chamber 6 5, and over The plenum box 50 has connectedthereto"Hills i a set of secondary nozzles 58 which direct jets of air at relatively high velocity rearwardly and downwardly above the knee of the arch 15 to secure a thorough mixing of the gases and such air as is here delivered at the throat of the furnace. This discharge of air from the nozzles 58 at the point where the direction of gases tends to change in the throat of the furnace is particularly useful in connection with the combustion of lines', that is, small which may becarrled up in the draft. "In addition,

air for combustion of any gases which have been consumed by contact with the over 130 not fire air delivered from the nozzles 53.

The fuel is lsubstantially re-Iv and refuse over the chamber 1.19

particles of solid matter,

it'serves to supply the necessary@ entinning .in

e; "105l emerges from under the arch land it.,

carbon over the latter part a suitable ash I across the width The spacing of the nozzles 58 transversely to the spacing of the nozzles 53, that is, about twenty inches apart, but obviously this may iiaring outwardly'to give the effect of a nozl zle for injecting of pressure prevailing in 'c'oking and consequent vrelease ing conditions at' approximate The next chamber carries the air at high velocity. The nozzles58 may be so shaped, but we have not found it necessary, to prov-ide other than a straight cylindrical opening at this point.

In the furnace hereinshown we have employeda blower" at. 26' which .supplies the requisite .delivery of 'air .under normal burn-j ly 1.25 inches of water.

For the fuel which we employ we find that it is necessary-- to'admit about 15' to 20% of the'total amount ofair employed through the over. lire nozzles'to secure the best results. This'figure naturally will vary with the character of the vfuel employed.

When the bloweris operating at a given speed. its delivery is substantially constant, and we .have found that the proportion o f over fire and' through fire air maybe suitably maintained by means of the valves 32 which controlalso he distribution of air throughout the length of the fuel bed.

1n Figure 2 we have shown, in the form of .agraph, approximately the conditions the various parts throughout the length of the fuel bed. Under normal running conditions the valve in duct 27- is set so as to deliver air at a pressure of substantially since vthe fuel entering here is substantially vgreen and is ignited as it enters the furnace; rInzthe next chamber 63 the pressure carried is; substantially is in Athis region where the greaterpart of of 'combustible gases occurs. The pressure in .the chamber G4 is of .the order of .60 inches of water, Some of the colring and burning ofthe fixed carbonoccurs' in this region ofthe fuel bed.

aira't a, pressure of .25 inches lof water, and the final chamber (i6 carries air at only .O5 inches'of water. The flows through the various sections do not exactly correspond to 'these pressures. but it will be seen that the central n part of the furnace in 'which combustion is of thev furnace corresponds a that is, grad.- ually decreasing to a narrow throat and then for proportioning fuel bed to mix the *.20 lnches of water,`

.70 inches of waternsince it j .taining` a. traveling box, under most rapid requiresthe greatest amount of The setting of the valves-32 may be varied for a given deliveryof air from the blower 26 to raise or lower the lgeneral level of pressures in the respectivechambers, andthereby to vary -the proportion of air delivered through the fire and over the fire.

The supplemental blower 52 furnishes means for maintaining the velocity at the nozzles 53 and 58 and this, in connection with the-individual shut o if means for these nozzles, permits of a regulation ofx the amount of air delivered andthe velocity at which it is delivered to as clse a degree as is necessary for'practic'al operation.

We do not intend to be limited to the details shown or described.`

' lVe claimtl l. In means for'burnirigfuel',hthe combination of a furnace havingmeans for maintaining* a traveling fuel bed, means for delivering air up' through the fuel 'bed to support combustion of the fuel in the bed, means the air deliveredthroug the respective .sections of the fuel bed, means for projecting a stream of relatively high velocity air into the furnace .above the vfu'elbed forwardly and `diagonally downwardly vinto the combustible gases arislng from the fuel bed to mix the same and securesibstantially complete combustion, an common air supply means Yfor both ofvafore said air delivery and air proiectingmeans.

A 2. In means for burning fuel, the `Viombination of a furnace having means Vfr maintaining a traveling fuel bed, a main win box, undenire air delivery means for delivering air from 'the main wind box up through .the fuel bedfor supporting combustion of the fuel in the bed, over fire air delivery means connected-to. the main wind box for projecting a locity lair'into the furnace'above the fuel bed .forwardly andl diagonally downwardly intohthecombustiblegases arising from the same and secure their delivering air under box, and valve a blower combustion,

the mam win pressure into means for controlling the proportions of air delivered through the fuel bed and above .the fuel bed, respectively. e

B. In means for burning fuel, the combination of afurnace having means for mainfuel bed, a main 'wind fire air delivery means for delivering air from the main wind box up through the fuel' bed for supporting combustion of the fuel in the fuel bed` an auxiliary wind box connected to the main wind box, over tire air delivery means for projecting air from the auxiliaryT wind box in a .stream of relatively high velocity into the furnace above the fuel bed forwardly and diagonally downwardly into the combustible gases arishan stream of relatively high veing from the fuel bed to Inix the saine and secure their combustion, a main blower for delivering under pressure all the air for both wind boxes, and a booster blower in the connection between the main and the auxiliary vwind boxes for increasing the pressure of air delivered through the auxiliary Wind box and its connected over fire airA delivery means.

of April, 1925.

' ARTHUR E. GRUNEBT.

ALEX D. BAILEY.

l our names this-7th clay 

